4). The present results show, for the first time, that Cdt crude venom can inhibit a chronic inflammatory response, the edema induced by the injection of BCG into

the paw of mice. This inhibitory action was long-lasting when the venom was injected before the BCG and efficient even when applied after the inflammatory stimulus, as shown in groups treated 6 or 11 days after the intraplantar injection of BCG. The long-lasting inhibitory response of the venom observed in this chronic inflammatory reaction was also observed when the Cdt venom was used in studies on the biological activities of macrophages and on the acute inflammatory response induced by carrageenan (Sousa e Silva et al., 1996; Nunes et al., 2007, 2010). To investigate mechanisms implicated in the inhibitory PTC124 cost action of Cdt venom on chronic

inflammation, we evaluated the participation of eicosanoids. Our data suggest that eicosanoids from the cyclooxygenase pathway are not involved in the mediation of the edema induced by BCG, nor in the inhibitory action of the Cdt venom because mice treated only with indomethacin presented edema similar to the control group, and pretreatment with this drug did not prevent the inhibitory effect of the Cdt venom Y-27632 manufacturer on the chronic inflammatory edema induced by BCG. Concerning the results obtained after treatment with dexamethasone, we observed that this drug inhibited the edema induced

by BCG in the acute (6 h) but not in the chronic (48 h) phase. However, when administered before the Cdt venom, this drug altered the inhibitory effect of venom in the chronic phase of the inflammatory process. This result points to the transient effect of dexamethasone in the inhibition of mediators involved however in both stages (acute and chronic) of inflammation induced by BCG, despite dexamethasone possessing high anti-inflammatory potency and prolonged action (biological half-life of 36–72 h) when compared to other corticosteroids (Schimmer and Parker, 2006). Moreover, the reversal of the inhibitory effect of the Cdt venom observed 48 h after BCG injection in the group pretreated with dexamethasone may suggest that the inhibitory effect induced by the venom is due to some endogenous anti-inflammatory mediator, most likely originating from the lipoxygenase pathway. This hypothesis was reinforced by the results obtained from groups pre-treated with zileuton, a drug that acts by inhibiting the enzyme 5-lipoxygenase. Studies indicate that products of this pathway, such as leukotrienes and lipoxins are able to modulate the inflammatory response and functions of leukocytes (Clarkson et al., 1998; Menezes-de-Lima et al., 2006; Serhan and Savil, 2005; Serhan, 2007).